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optparse.coffee

#

A simple OptionParser class to parse option flags from the command-line. Use it like so:

parser  = new OptionParser switches, helpBanner
options = parser.parse process.argv

The first non-option is considered to be the start of the file (and file option) list, and all subsequent arguments are left unparsed.

 
exports.OptionParser = class OptionParser
#

Initialize with a list of valid options, in the form:

[short-flag, long-flag, description]

Along with an an optional banner for the usage help.

 
  constructor: (rules, banner) ->
    @banner = banner
    @rules  = buildRules rules
#

Parse the list of arguments, populating an options object with all of the specified options, and returning it. options.arguments will be an array containing the remaning non-option arguments. This is a simpler API than many option parsers that allow you to attach callback actions for every flag. Instead, you're responsible for interpreting the options object.

 
  parse: (args) ->
    options = arguments: []
    args    = normalizeArguments args
    for arg, i in args
      isOption = !!(arg.match(LONG_FLAG) or arg.match(SHORT_FLAG))
      matchedRule = no
      for rule in @rules
        if rule.shortFlag is arg or rule.longFlag is arg
          value = if rule.hasArgument then args[i += 1] else true
          options[rule.name] = if rule.isList then (options[rule.name] or []).concat value else value
          matchedRule = yes
          break
      throw new Error "unrecognized option: #{arg}" if isOption and not matchedRule
      if not isOption
        options.arguments = args[i...args.length]
        break
    options
#

Return the help text for this OptionParser, listing and describing all of the valid options, for --help and such.

 
  help: ->
    lines = ['Available options:']
    lines.unshift "#{@banner}\n" if @banner
    for rule in @rules
      spaces  = 15 - rule.longFlag.length
      spaces  = if spaces > 0 then Array(spaces + 1).join(' ') else ''
      letPart = if rule.shortFlag then rule.shortFlag + ', ' else '    '
      lines.push '  ' + letPart + rule.longFlag + spaces + rule.description
    "\n#{ lines.join('\n') }\n"
#

Helpers

 
             		           
                               
                            
                 #               
               
Regex matchers for option flags.
             		                            
LONG_FLAG  = /^(--\w[\w\-]+)/
SHORT_FLAG = /^(-\w)/
MULTI_FLAG = /^-(\w{2,})/
OPTIONAL   = /\[(\w+(\*?))\]/
             		           
                               
                            
                 #               
               
Build and return the list of option rules. If the optional short-flag is
unspecified, leave it out by padding with null.
             		                            
buildRules = (rules) ->
  for tuple in rules
    tuple.unshift null if tuple.length < 3
    buildRule tuple...
             		           
                               
                            
                 #               
               
Build a rule from a -o short flag, a --output [DIR] long flag, and the
description of what the option does.
             		                            
buildRule = (shortFlag, longFlag, description, options) ->
  match     = longFlag.match(OPTIONAL)
  longFlag  = longFlag.match(LONG_FLAG)[1]
  options or= {}
  {
    name:         longFlag.substr 2
    shortFlag:    shortFlag
    longFlag:     longFlag
    description:  description
    hasArgument:  !!(match and match[1])
    isList:       !!(match and match[2])
  }
             		           
                               
                            
                 #               
               
Normalize arguments by expanding merged flags into multiple flags. This allows
you to have -wl be the same as --watch --lint.
             		                            
normalizeArguments = (args) ->
  args = args.slice 0
  result = []
  for arg in args
    if match = arg.match MULTI_FLAG
      result.push '-' + l for l in match[1].split ''
    else
      result.push arg
  result